To investigate the possible role of insulin per se in the thermic response to glucose/insulin infusions, respiratory exchange measurements were performed on eight healthy young men for 45 min before and 210 min after somatostatin infusion. Two tests were performed on separate days and each had two consecutive phases of 90 min each. Test 1. Two different rates of glucose uptake were imposed, one at euglycemia (phase 1) and the other at hyperglycemia (phase 2) while insulinemia was maintained constant throughout. Test 2. Glucose uptake was maintained constant throughout while insulin was infused at two different rates: 1 mU/kg per min with hyperglycemia (phase 1) and 6.45 mU/kg per min with "euglycemia" (phase 2). The thermic effect of glucose and insulin, obtained from phase 1 in both tests, was 5.9 +/- 1.2 and 5.8 +/- 0.5% (NS) of the energy infused, respectively. A step increase in glucose uptake alone, test 1, phase 2, (0.469 +/- 0.039 to 1.069 +/- 0.094 g/min) caused an increase in energy expenditure of 0.14 +/- 0.03 kcal/min (thermic effect 5.9 +/- 1.1%). When insulin was increased by 752 +/- 115 microU/ml, with no change in glucose uptake, energy expenditure rose by 0.05 +/- 0.02 kcal/min, which correlated with the increase in plasma catecholamines. It is concluded that a large proportion of the thermic response to glucose/insulin infusions is due to glucose metabolism alone. The thermic effect of insulin is small and appears to be mediated by the sympathetic nervous system; thus at physiological insulin concentrations, the thermic effect of insulin per se is negligible.
L Christin, C A Nacht, O Vernet, E Ravussin, E Jéquier, K J Acheson
22 homosexual or narcotic addict patients at risk for acquired immunodeficiency syndrome (AIDS) or with AIDS, were studied for the presence of antiimmunoglobulin antibodies and circulating immune complexes (20 were thrombocytopenic, 6 had AIDS). Circulating immune complex levels were 10-fold higher than levels in normal subjects. IgG anti-F(ab')2 antibodies were noted in homosexual as well as narcotic addict patients. Of 16 homosexual patients, 7 had IgG anti-F(ab')2 antibody of moderate to marked titer with broad reactivity against autologous, homologous, and control F(ab')2 fragments. Three others demonstrated limited reactivity against one or two F(ab')2 fragments. The remaining six patients were negative. Six of six narcotic addict patients had IgG anti-F(ab')2 antibody, five with limited reactivity, one with broad reactivity. In contrast, neither elevated circulating immune complexes nor anti-F(ab')2 antibodies were detectable in six autoimmune thrombocytopenic patients. Anti-F(ab')2 antibody could be affinity purified from serum or circulating immune complexes. Anti-F(ab')2 reactivity correlated with circulating immune complex levels, r = 0.83, P less than 0.01.
J R Yu, E T Lennette, S Karpatkin
Circulating osteocalcin, which normally reflects the rate of bone formation, is elevated in uremia. In 18 patients receiving maintenance hemodialysis, serum osteocalcin levels were directly related to the bone formation rate (r = 0.88, P less than 0.001), osteoblastic osteoid surface density (r = 0.65, P less than 0.01), and osteoclastic resorptive surface density (r = 0.75, P less than 0.001). Multiple regression analysis showed that osteocalcin levels remained positively correlated with osteoclastic resorption when the bone formation rate was held constant (P less than 0.01). The intimation that the coupling of bone formation and resorption could not explain the relationship between osteocalcin and resorption led us to determine whether fragments of this abundant matrix protein are released by bone resorption and retained in uremia. Sera from dialysis patients with renal osteodystrophy were fractionated by sequential gel filtration and HPLC, and assayed for immunoreactive osteocalcin. When normal serum was analyzed, a single sharp peak was found. In pooled sera from patients with high osteoclastic resorptive surfaces identified by histomorphometry, we found five additional immunoreactive peaks, while three additional peaks were detected in sera from patients with lower osteoclastic surfaces. Bio-Gel P-10 chromatography showed that these multiple peaks were of lower molecular weight than intact osteocalcin. We suggest that the liberation of bone matrix by osteoclasts contributes to the circulating osteocalcin immunoreactivity in uremia.
C M Gundberg, R S Weinstein
Insulinlike growth factors (IGF) act qualitatively like insulin on insulin target tissues in vitro. In the circulation in vivo they are bound to specific carrier proteins. In this form or when continuously infused into hypophysectomized (hypox) rats they do not exert acute insulinlike effects on glucose homeostasis. This study definitively shows that intravenous bolus injections of pure IGF I or II act acutely on glucose homeostasis: they lower the blood sugar, enhance the disappearance of U-[14C]glucose from serum and increase its incorporation into diaphragm glycogen in normal and hypox rats in the presence of antiinsulin serum. The same effects were obtained with recombinant human IGF I injected intravenously either with or without antiinsulin serum into normal rats. Free fatty acid levels decreased transiently only in normal animals. Lipid synthesis from glucose in adipose tissue was not stimulated in hypox and barely stimulated in normal rats. The half-life of injected IGF I or II in normal rats (approximately 4 h) is strikingly different from that in hypophysectomized rats (20-30 min) and appears to depend on the growth hormone-induced 150,000-200,000-mol wt IGF carrier protein that is lacking in hypophysectomized rats. 15 min after the bolus serum IGF I and II concentrations were similar to steady state levels during long-term infusion in hypox rats. Free IGF was barely detectable, however, in the infused animals, whereas 40-100% was found free 15 min after the bolus. These observations for the first time confirm the hypothesis that only free IGF, but not the IGF carrier protein complex, is bioavailable to insulin target tissues.
J Zapf, C Hauri, M Waldvogel, E R Froesch
We have previously demonstrated low levels of immunoreactive (ir)-beta-endorphin (beta-EP) and ir-ACTH in a subpopulation of mouse spleen macrophages, which is consistent with an involvement of opioid peptides in modulation of immune responses. Gel chromatography studies suggested the presence of an approximately 3.5,000-molecular weight (mol wt) species, putatively beta-EP, an approximately 11.5,000-mol-wt species, putatively beta-lipotropin, and a higher molecular weight species (putative beta-EP precursor, pro-opiomelanocortin (POMC). In this study we have extended our original findings by demonstrating the presence of messenger RNA for POMC by the use of a complementary DNA probe and Northern blot analysis of extracts of mouse and rat spleen. In addition, using high performance liquid chromatography (HPLC), we have shown that the major endorphin species in mouse spleen macrophages is beta-EP1-31, and that there are smaller amounts of each of the acetylated forms, N-acetyl-beta-EP1-16 (alpha-endorphin), N-acetyl-beta-EP1-17 (gamma-endorphin), N-acetyl-beta-EP1-27, and N-acetyl-beta-EP1-31. We interpret these studies as showing that (a) the spleen is an organ of POMC synthesis and that (b) the predominant COOH-terminal product of macrophage POMC is the opiate-receptor active species beta-EP1-31.
S J Lolait, J A Clements, A J Markwick, C Cheng, M McNally, A I Smith, J W Funder
The present study was designed to determine the effects of pulmonary vascular pressure, vascular injury, and pulmonary edema on regional blood volume (Vr) and regional red blood cell (RBC) transit time (Tr) in the lung. The experiments were carried out in 15 dogs. Six served as controls, six had oleic acid-induced pulmonary edema (OAPE), and three had high pressure pulmonary edema (HPPE). Regional blood flow (Qr) was measured with 99mTc macroaggregates, Vr with 51Cr homologous RBC, and regional transit time was calculated (Vr/Qr). The dogs were killed, and the lungs removed and sampled completely. Regional extravascular lung water (EVLW) was measured in grams per gram of dry lung and ranged from 3.7 +/- 1.1 in the control group to 6.0 +/- 1.3 in OAPE and 5.6 +/- 0.6 in HPPE. The data show that in normal lungs, increased Qr was associated with a recruitment of blood volume. In OAPE, data show that regional blood volume was decreased and that vascular injury and edema formation interfered with a further increase in Vr as Qr increased. In HPPE, Vr has already fully distended and it changed little with increased blood flow. We conclude that oleic acid-induced pulmonary injury and edema interfere with vascular recruitment and shorten regional RBC transit times. HPPE, on the other hand, is associated with normal regional RBC transit times because the vessels are fully recruited.
J Y Tsang, J S Montaner, J C Hogg
The present study was designed to compare high pressure pulmonary edema (HPPE) and oleic acid-induced low pressure pulmonary edema (OAPE) in dogs when similar amounts of extra vascular water were present in the lung. The high pressure edema was produced by intravenous fluid overload and by inflating an aortic balloon catheter (n = 6). The low pressure edema was produced by the injecting 0.08 mg/kg oleic acid suspended in 5 ml saline (n = 6). Comparison of the difference between initial control measurements and final measurements in the edematous states showed that the animals with OAPE had a greater fall in percent oxygen saturation and a greater increase in shunt fractions. The light microscopic studies showed that OAPE was associated with greater amounts of alveolar flooding than HPPE where the edema fluid was located to a greater extent in the peribronchial interstitial space. The electron microscopy studies showed that the alveolar flooding in OAPE was associated with epithelial disruption, and tracer studies carried out in rabbits showed that dextran (150,000 mol wt) could pass from blood to airspace and that dextran (40,000 mol wt) could pass from air-space to blood in OAPE. We conclude that epithelial disruption is responsible for the excessive alveolar flooding in OAPE and that this results in a greater impairment in gas exchange.
J S Montaner, J Tsang, K G Evans, J B Mullen, A R Burns, D C Walker, B Wiggs, J C Hogg
To determine whether a resistance to insulin in type 1, insulin-dependent diabetes mellitus (IDDM) is extended to both glucose and amino acid metabolism, six normal subjects and five patients with IDDM, maintained in euglycemia with intravenous insulin administration, were infused with L-[4,5-3H]leucine (Leu) and [1-14C]alpha ketoisocaproate (KIC). Steady-state rates of leucine-carbon appearance derived from protein breakdown (Leu + KIC Ra) and KIC (approximately leucine) oxidation were determined at basal and during sequential euglycemic, hyperinsulinemic (approximately 40, approximately 90 and approximately 1,300 microU/ml) clamps. In the euglycemic postabsorptive diabetic patients, despite basal hyperinsulinemia (24 +/- 6 microU/ml vs. 9 +/- 1 microU/ml in normals, P less than 0.05), Leu + KIC Ra (2.90 +/- 0.18 mumol/kg X min), and KIC oxidation (0.22 +/- 0.03 mumol/kg X min) were similar to normal values (Leu + KIC Ra = 2.74 +/- 0.25 mumol/kg X min) (oxidation = 0.20 +/- 0.02 mumol/kg X min). During stepwise hyperinsulinemia, Leu + KIC Ra in normals decreased to 2.08 +/- 0.19, to 2.00 +/- 0.17, and to 1.81 +/- 0.16 mumol/kg X min, but only to 2.77 +/- 0.16, to 2.63 +/- 0.16, and to 2.39 +/- 0.08 mumol/kg X min in the diabetic patients (P less than 0.05 or less vs. normals at each clamp step). KIC oxidation decreased in normal subjects to a larger extent than in the diabetic subjects. Glucose disposal was reduced at all insulin levels in the patients. In summary, in IDDM: (a) Peripheral hyperinsulinemia is required to normalize both fasting leucine metabolism and blood glucose concentrations. (b) At euglycemic hyperinsulinemic clamps, lower glucose disposal rates and a defective suppression of leucine-carbon appearance and oxidation were observed. We conclude that in type 1 diabetes a resistance to the metabolic effects of insulin on both glucose and amino acid metabolism is present.
P Tessari, R Nosadini, R Trevisan, S V De Kreutzenberg, S Inchiostro, E Duner, G Biolo, M C Marescotti, A Tiengo, G Crepaldi
The treatment of verapamil toxicity was examined in lightly sedated dogs. Verapamil, administered as a bolus (0.72 mg/kg) followed by a continuous infusion (0.11 mg/kg per min), decreased cardiac output (CO) from 3.1 +/- 0.1 to 1.7 +/- 0.1 liter/min (P less than 0.001), heart rate (HR) from 85 +/- 4 to 57 +/- 3 beats/min (P less than 0.001), left ventricular derivative of pressure with respect to time (LV dP/dt) from 2,085 +/- 828 to 783 +/- 78 mm Hg/s (P less than 0.001), mean aortic pressure (AO) from 77 +/- 4 to 38 +/- 2 mm Hg (P less than 0.001) and stroke volume from 39 +/- 3 to 28 +/- 2 ml/beat (P less than 0.01). In verapamil-toxic animals isoproterenol increased HR, CO, LV dP/dt, and AO; calcium chloride increased LV dP/dt and AO; norepinephrine, epinephrine, and dopamine increased CO, AO, and LV dP/dt, atropine increased HR, CO, and AO. Phenylephrine (13-55 micrograms/kg per min) produced no changes except a small increase in AO while very high dose phenylephrine (300 micrograms/kg per min) increased AO, CO, and LV dP/dt. 4-Aminopyridine (4-AP) increased HR, CO, LV dP/dt, and AO. When administered prior to verapamil, 4-AP prevented the development of verapamil toxicity as shown by the significantly higher AO (P less than 0.001), CO (P less than 0.01), and LV dP/dt (P less than 0.01) when 4-AP followed by verapamil was compared to verapamil alone. In conclusion, there does not appear to be a single specific therapy for verapamil toxicity, however it can be partially corrected by presently available pharmacologic therapy and 4-AP.
R Gay, S Algeo, R Lee, M Olajos, E Morkin, S Goldman
In vitro and in vivo studies have suggested that human complement component C5a plays a key role in neutrophil injury in the adult respiratory distress syndrome (ARDS). First, using leukocyte aggregometry, we demonstrated that the addition of a recently developed rabbit anti-human polyclonal antibody to C5a des arg to endotoxin-activated plasma prevented leukocyte aggregation in vitro. We then administered the anti-C5a des arg antibody to septic primates (Macaca fascicularis). Three groups of primates, control, septic, and anti-C5a antibody treated septic, were studied (n = 4 in each group). A 30-min infusion of Escherichia coli (1 X 10(10)/kg) resulted in severe sepsis and ARDS. Primates were killed 4 h after completion of the E. coli infusion. Septic animals not treated with anti-C5a antibody had 75% mortality (3/4), decreased oxygenation, severe pulmonary edema, and profound hypotension. Septic primates treated with anti-C5a antibodies did not die and did not develop decreased oxygenation (P less than 0.05) or increased extravascular lung water (P less than 0.05). They also had a marked recovery in their mean arterial blood pressure (P less than 0.05). This study demonstrates that treatment with rabbit anti-human C5a des arg antibodies attenuates ARDS and some of the systemic manifestations of sepsis in nonhuman primates.
J H Stevens, P O'Hanley, J M Shapiro, F G Mihm, P S Satoh, J A Collins, T A Raffin